设计模式C++学习笔记之二（Proxy代理模式）

c++设计模式总结，出处见 点击打开链接

代理，一看名字就知道这只是个中介而已，真实的执行者在代理的后面呢。cbf4life在他的书里提的例子也很有趣，更详细的内容及说明可以参考原作者博客：cbf4life.cnblogs.com。现在贴代码，以方便随用随取。

2.1.解释

main()，西门庆

IKindWomen，接口

CWangPo，代理

CPanJinLian，实际执行者之一

CJiaShi，实际执行者之二

说明：代理和实际执行者派生于共同的接口，代理拥有实际执行者的实例。代理的每一个函数（接口的实现函数），直接调用实际执行者的对应接口函数。

注意：代理只是简单的装载，然后调用实际执行者的函数。

看代码：

//IKindWomen.h#pragma onceclass IKindWomen{public:    IKindWomen(void);    virtual ~IKindWomen(void);    virtual void MakeEyesWithMan() = 0;    virtual void HappyWithMan() = 0;};//WangPo.h#pragma once#include "ikindwomen.h"class CWangPo :    public IKindWomen{public:    CWangPo(IKindWomen *pKindWomen);    ~CWangPo(void);    void HappyWithMan(void);    void MakeEyesWithMan(void);private:    IKindWomen *m_pKindWomen;};//WangPo.cpp#include "StdAfx.h"#include "WangPo.h"CWangPo::CWangPo(IKindWomen *pKindWomen){    this->m_pKindWomen = pKindWomen;}CWangPo::~CWangPo(void){    delete this->m_pKindWomen;}void CWangPo::HappyWithMan(){    this->m_pKindWomen->HappyWithMan();}void CWangPo::MakeEyesWithMan(void){    this->m_pKindWomen->MakeEyesWithMan();}//PanJinLian.h#pragma once#include "ikindwomen.h"class CPanJinLian :    public IKindWomen{public:    CPanJinLian(void);    ~CPanJinLian(void);    void HappyWithMan(void);    void MakeEyesWithMan(void);};//PanJinLian.cpp#include "StdAfx.h"#include "PanJinLian.h"#include <iostream>using std::cout;using std::endl;CPanJinLian::CPanJinLian(void){}CPanJinLian::~CPanJinLian(void){}void CPanJinLian::HappyWithMan(void){    cout << " 潘金莲和男人做那个... ... " << endl;}void CPanJinLian::MakeEyesWithMan(void){    cout << " 潘金莲抛媚眼 " << endl;}//JiaShi.h#pragma once#include "ikindwomen.h"class CJiaShi :    public IKindWomen{public:    CJiaShi(void);    ~CJiaShi(void);    void HappyWithMan(void);    void MakeEyesWithMan(void);};//JiaShi.cpp#include "StdAfx.h"#include "JiaShi.h"#include <iostream>using std::cout;using std::endl;CJiaShi::CJiaShi(void){}CJiaShi::~CJiaShi(void){}void CJiaShi::HappyWithMan(void){    cout << " 贾氏和男人做那个... ... " << endl;}void CJiaShi::MakeEyesWithMan(void){    cout << " 贾氏抛媚眼 " << endl;}//Proxy.cpp#include "stdafx.h"#include "WangPo.h"#include "PanJinLian.h"#include "JiaShi.h"#include <iostream>using std::cout;using std::endl;void DoPanJinLian(){    CWangPo *pWangPo;    // 西门庆想找潘金莲，让王婆来安排。    pWangPo = new CWangPo(new CPanJinLian());    pWangPo->MakeEyesWithMan();    pWangPo->HappyWithMan();    delete pWangPo;}void DoJiaShi(){    CWangPo *pWangPo;    // 西门庆想找贾氏，让王婆来安排。    pWangPo = new CWangPo(new CJiaShi());    pWangPo->MakeEyesWithMan();    pWangPo->HappyWithMan();    delete pWangPo;}int _tmain(int argc, _TCHAR* argv[]){    // 西门庆想找潘金莲    DoPanJinLian();    // 西门庆想找贾氏    DoJiaShi();    _CrtSetDbgFlag(_CRTDBG_LEAK_CHECK_DF | _CRTDBG_ALLOC_MEM_DF);    _CrtDumpMemoryLeaks();    system("pause");    return 0;}

看起来代理模式的结构和策略模式类似，都是由一个类来装载接口的一个实例，策略模式是CContext来装载，代理模式是CWangPo来装载。CContext不是从IStrategy派生，所以不需要实现IStrategy接口函数，而CWangPo是从IKindWomen派生的所以CWangPo很清楚CPanJinLian和CJiaShi的接口函数。这就是代理，代理人知道被代理人能干的事情即函数，所以代理人可以成为中介。

代理模式可以很好的将前后端分开，实现了松散耦合。代理模式属于结构型模式。上图仍然是例子中用到的类相关图，并不是代理模式的抽象类图。这样的类图更容易理解代理模式。抽象类图当然具有更高的抽象层次，但不利于理解。